The purpose of this core component is to provide expertise and technical support to the design and execution of experimental approaches utilizing flow cytometry analysis and physical separation techniques to address basic and applied research questions in the area of HIV-immune cell interactions. The core facility will provide technical resources for immune cell phenotyping, physical separation and isolation of cell phenotypes, analysis of cell activation functions, and analysis of molecular, expression vector constructs. The equipment to perform these functions includes a Becton-Dickinson FACStar Plus cell sorter with a fifth debtor for 3- color analysis, and a Coulter Elite cell sorter with dual lasers plus a UV laser for calcium flux and cellular DNA analyses. Support personnel include a highly-trained and experienced technician for preparation and/or separation, and antibody staining of cell samples. The Core Director, who is experienced in flow cytometry methodology and experimental design, will provide consultation and research direction to investigator users of the facility. The major goal of this basic science component is to provide the intellectual environment and the material resources to enable junior investigators to apply flow cytometry technology to appropriate research projects and to encourage innovative pilot studies by more established investigators.